Between 2000 and 2003 over 100 leek plantings and two nurseries in four states were surveyed to determine the most significant disease problems of leeks in Australia. Four diseases were identified causing economic loss: Fusarium foot rot (caused by one of four Fusarium species), bacterial blight (Pseudomonas syringae pv. porri), leaf blight (Stemphylium sp.) and purple blotch (Alternaria porri). Other diseases detected but not of major importance included pink root (Pyrenochaeta terrestris), smudge (Colletotrichum circinans), Botrytis leaf spot (Botrytis cinerea), downy mildew (Peronospora destructor), Leek yellow stripe virus, Shallot latent virus and Onion yellow dwarf virus. Parasitic nematodes recovered from leek soil included Paratrichodorus sp. (stubby root), Pratylenchus sp. (root lesion), Ditylenchus sp. (stem and bulb) and Scutellonema sp. (spiral nematode). The physiological disorder, oedema, caused cosmetic damage in some seasons.